Regensburg 2016 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 45: Brownian Motion and Transport

DY 45.2: Vortrag

Mittwoch, 9. März 2016, 16:45–17:00, H46

Friction dynamics of colloidal crystal layers in shear flow — •Sascha Gerloff and Sabine H. L. Klapp — Institut für Theoretische Physik, Technische Universität Berlin, Hardenbergstraße 36, 10623 Berlin, Germany

Friction at the nanoscale is characterized by complex non-equilibrium dynamics, whose understanding is relevant for various different systems. An important example is the frictional dynamics of two atomically flat crystalline surfaces in contact, which currently attract strong attention from both, the theoretical and experimental point of view. Here we present results from overdamped Brownian dynamic simulations to investigate the non-equilibrium dynamics of confined colloidal suspensions in shear flow. We focus on slit-pore confinement where the colloids form colloidal crystal layers. We first revisit the shear-induced dynamics of a one-component bilayer system, displaying a pronounced de-pinning transition related to shear induced melting. Using a one-particle model we estimate the critical shear rate for this transition. As a second step we investigate the frictional dynamics of layers with different crystalline structure. To this end, we introduce an additional layer of small colloids to the system and stabilize it via a constant force. For this system, the dynamics at small shear rates is dominated by a local transport mechanism related to density excitations. Investigating the properties and dynamics of these density excitations is key to understand the overall dynamics of the layer. For small shear rates, we find the relative velocity of the layer to be proportional to the number and velocity of the density excitations.